The goal of the proposed research is to understand the behavioral and physiological functioning of the chemical senses, with an emphasis on taste. To approach an understanding of gustation we are using a mammalian species, the laboratory mouse (Mus), that is amenable to behavioral, genetic, and physiological experimentation. The overall plan involves three phases. In the first phase a screening procedure is employed to identify existing strains of mice which are genetically extreme in response to specific chemical tastants. Further psychophysical and sensory electrophysiological techniques are applied to validate screening results. In the second phase methods of behavior genetics are applied to identify the precise nature of the genetic involvement in extreme tasting phenotypes, and to develop special genetic stocks for rigorous investigation of taste mechanisms. In the third phase the genetic stocks which result from the second phase are used to analyze properties and mechanisms of taste at levels from the biochemical to the behavioral. At the present stage of the project the primary emphasis is development of special genetic stocks and their utilization in taste experiments. Specific taste-relevant identified stocks now available or nearing completion include inbred lines, segregating population, recombinant inbred sets, and a specially constructed replication congenic inbred set. The primary health relatedness of this research is that taste allows monitoring of food taken into the oral cavity and detects and discriminates the many chemical compounds of this food. Taste factors and related dietary concerns are of central relevance to health in a wide variety of matters ranging from obesity to cachexia.